Weighing the pros and cons of the corn-based fuel.
Take a look at the back of some early 2000s General Motors vehicles, and you'll notice a black-and-yellow badge that reads “Flex Fuel.” While this is not quite as exciting as the name suggests, this term refers to the fact that these vehicles can run on both gasoline and ethanol. You may have heard the word before, but what exactly is ethanol? And is ethanol actually any better than gasoline?
The ethanol that you pump into your car is essentially ethyl alcohol, the same alcohol that you can consume as a beverage. It is created using a similar process to the way beer is produced, first using an enzyme to convert the starch from the corn into sugars before utilizing yeast to ferment the sugar and create ethanol.
Usually, the ethanol is mixed with a small amount of gasoline as required by law to make the ethanol non-potable—preventing you from chugging it on a Friday night when you run out of vodka. Common ethanol mixtures are designated E10, E15, and E85, with the number representing the percent volume of ethanol. Since 2011, all new vehicles have been manufactured to run on E10. The flex fuel vehicles mentioned earlier can run on both E85 (which is actually anywhere from 50-85% ethanol) and gasoline.
So if you own a flex fuel vehicle, is there any benefit to opting for E85 when you’re at the pump? There are, in fact, a few disadvantages to ethanol. For starters, ethanol has one-third less energy than gasoline, so while there's no noticeable performance loss on ethanol, it will result in a slight decrease in fuel economy.
There are also a few issues to keep in mind concerning ethanol and engine maintenance. One of the properties of ethanol is that it attracts and absorbs water. If enough water accumulates, fuel-water contamination occurs. This becomes a problem when a vehicle has been sitting still for some time, as the water and fuel will separate, leading the engine to intake only water instead of fuel causing costly damage.
Additionally, alcohol can cause corrosion in the fuel system, especially an issue on older vehicles. Finally, from a more big picture standpoint, it takes a lot of land, and therefore a lot of corn, to produce just a small amount of ethanol, as one acre of corn converts to only 328 gallons of ethanol.
There is a couple of major positives to ethanol, however. Ethanol is highly resistant to preignition, similar to 105 octane gasoline. Therefore, ethanol is widely used in the one place where you need super precise ignition timing and have high compression ratios while also not caring about fuel economy: racing.
Additionally, race teams care less about engine wear since their engines are not driven on a daily basis and can be replaced after only several races. Ethanol’s other benefit is that it emits fewer greenhouse gasses than gasoline, making it an oxygenate and therefore satisfying the Clean Air Act. This means ethanol is often designated as a stand-in alternate fuel until we find a suitable replacement or fully expand the electric and hydrogen networks.
So what’s the verdict? Well, if your vehicle can handle E85 and you want to help the environment, go for the ethanol. And if you’re a race car driver…well chances are you’re already using it.